The present invention relates generally to wireless communication systems, and particularly to RF signal transmission in such systems.
Wireless communication systems, such as cellular telephone networks, are typically based on one or more standardized communication schemes. Examples of air interface standards include a variety of schemes used with varying degrees of prevalence around the world. The Telecommunication Industry Association (TIA) and the Electronic Industry Association (EIA) publish as standard known as TIA/EIA-136, which is a commonly used North American standard. The TIA/EIA-136 standard provides digital communication and data services based on Time Division Multiple Access (TDMA) techniques at both 800 MHz and 1900 MHz. The Global System for Mobile Communications (GSM) standard is roughly equivalent and finds broad usage in Europe. Other widely used standards include IS-95 and IS-2000, which represent Code Division Multiple Access (CDMA) standards providing data and communication services at 800 MHz and 1900 MHz.
IS-2000 is a developing standard, coming under the umbrella of the so-called third generation (3G) of wireless communication systems. The wideband CDMA (WCDMA) 3G standard represents a rough European equivalent of the IS-2000 initiative. While IS-2000 has similarities with the earlier IS-95 CDMA standard, IS-2000 extends the bandwidth utilization of IS-95, providing system operators with additional service capability. In improving bandwidth utilization and extending other service features of IS-95, the IS-2000 standard changes certain signaling requirements between mobile terminals and base stations.
All of these standards, to varying degrees, have different signaling requirements. However, to provide users with maximum versatility, wireless communication devices commonly provide compatibility with multiple communication standards. While this is a matter of practicality from the consumer's perspective, it imposes certain system design challenges. For example, economic and physical limitations dictate that all or most of the same transmit and receive hardware within a mobile device be used for all of the air interface standards supported by that device.